Compunded turbine oils



United States Patent COMPOUNDED TURBINE OILS Raymond T. Kern, Jiz, Allentown, Pa., and John G.

Peters, Audubon, N. J., assiguors to Gulf Oil Corporation, Pittsburgh, Pa., a corporation of Pennsylvama No Drawing. Application August 19, 1954, Serial No. 451,039

8 Claims. (Cl. 252-325) This invention relates to lubricating compositions and more particularly to compounded'turbine oils adapted to prevent rusting and corrosion of metal turbine parts which are exposed to moisture.

Various lubricating compositions have heretofore been disclosed for lubricating steam turbines but the prior compositions have not been entirely satisfactory. Some of the prior compositions have exhibited good resistance to oxidation but they have not given complete protection against rusting and corrosion of metal turbine parts which are exposed to moisture. Other compositions have given good protection against rusting and corrosion in the presence of moisture, but the moisture has given rise to the formation of an undesirable precipitate.

The present invention is based upon a particularly efiective lubricating composition having good resistance to oxidation combined with good lubricating characteristics and corrosion and rust-inhibiting properties with the added advantage that no precipitate is formed when the composition becomes contaminated with water.

The improved lubricating composition of this invention consists essentially of a homogeneous mixture of lubricating oil, a metal alkyl thiophosphate, an alkyl phenol, a substantially neutral addition product of isoamyl octyl acid phosphate with primary fatty amines containing from 8 to 18 carbon atoms, and an acid ester of (1) a dimeric acid derived from an unsaturated fatty acid containing from 6 to 22 carbon atoms and having from 2 to 3 ethylenic linkages per molecule and (2) a partial ester of a fatty acid containing from 12 to 24 carbon atoms and an alkitol anhydride. An improved lubricating composition can be prepared by incorporating in an oil a metal alkyl thiophosphate, an alkyl phenol and a substantially neutral addition product of isoamyl octyl acid phosphate with primary fatty amines containing from 8 to 18 carbon atoms. While the composition thus obtained has good corrosion and rust-inhibiting properties, the composition has a disadvantage in that it forms a precipitate when contaminated with water.

We do not wish to be limited to any theory with respect to the reason that a precipitate is formed when a small amount of water contaminates the composition containing no acid ester. However, it appears that the metal alkyl thiophosphate and the fatty amine salt of isoamyl octyl acid phosphate are incompatible in the presence of moisture and that they react to form a material which settles out of solution. This settling out is undesirable in that useful constituents are removed from the lubricating oil thus cutting down on its effectiveness. In addition to affecting the usefulness of the composition, its appearance is impaired as it becomes cloudy and is heterogeneous instead of being homogeneous.

We have found that these undesirable properties can be overcome by incorporating in the composition a small amount of an acid ester of (1) a dimeric acid derived from an unsaturated fatty acid containing from 6 to 22 carbon atoms and having from 2 to 3 ethylenic linkages 2,789,951 Patented Apr. 23, 1957 ICC per molecule and (2). apartial ester of a fatty acid containing from 12 to 24 carbon atoms and an alkitol anhydride.

The-lubricating oil to which the other constituents are added is advantageously a highlyrefined paraflinic oil. By the term highly refined paraffinic oil we meana petroleum lubricating oil which has been refined by one of the more drastic refining methods known in the art, for example, by conventional aluminum chloride refining or by a solvent extraction adapted to remove all or substantially all of the unsaturated and naphthenicconstituents of the oil. Aluminum chloride refined'br solvent extracted paraffinic base oil, such as a Pennsylvania on, provides an excellent base oil for the composition of the invention. However, drastically refined Mid-Continent and Gulf Coastal oil may also be used. a

The metal alkyl thiophosphates which can be used in accordance with the invention are advantageously those whose metal component is a metal of group II of Mendeleefls periodic arrangement of the elements. Included within this group are magnesium, calcium, zinc, strontium, cadmium and barium. However, other metals including aluminum, copper, lead, tin, iron and manganese can also be employed. The alkyl substituents are preferably those containing between 3 and 12 carbon atoms.- Examples of the alkyl groups which can be used are butyl, particularly tertiary butyl, amyl, isoamyl, tertiary amyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, and the like. While the mono-alkyl esters can be used, the di-alkyl esters are particularly suitable for the purposes of the invention. An example of a particularly eifective com pound which can be used is zinc dihexyl thiophosphate. When zinc dihexyl thiophosphate is used, it is preferably used in an amount between about 0.01 and 0.1 percent by Weight based on the weight of the total composition. An amount greater than about 0.1- percent'is undesirable in that the neutralization number of the final product is increased above the maximum set for commercial use.

The alkyl phenol which is used in accordance with the invention is advantageously a dior tri-alkylated phenol or cresol with at least one of the alkyl groups being a tertiary alkyl group. The alkyl groups are preferably those containing between 3 and 12 carbon atoms. Good results can be obtained with a tri-tertiary butyl phenol or a di-tertiary butyl cresol. Examples of the preferred alkylated phenols are 2,4,6-tri-tertiary-butylphenol, 2,6-

di-tertiary-butyl-4-methylphenol and bis(2-hydroxy-3- tertiary-butyl-S-methylphenyl)methane. The alkyl phenols are advantageously used in amounts of about 0.1 to about 2.0 percent by weight based on the weight of the :1; total composition.

The. fatty amine salt of isoamyl octyl acid phosphate which can be used in accordance with the invention is prepared by reacting isoamyl octyl acid phosphate with a primary fatty amine containing from 8 to 18 carbon atoms. One example of a primary fatty aminesuitable for the purpose of this invention is cocoamine, which a commercially available product prepared by converting coconut oil fatty acids into the corresponding amine. It consists mostly of monolauryl amine with minor amounts r of adjacent homologues. The cocoamine salt of isoamyl octyl acid phosphate and its preparation are fully described:

in U. S. Patent No. 2,371,851 which issued on March 20, 1945, to Herschel G. Smith and Troy L. Cantrell. As disclosed in said patent, the cocoamine salt of isoamyl octyl acid phosphate can be readily prepared by reacting cocoamine with isoamyl octyl acid phosphate in approximately equimolecular ratios, the reaction being so controlled as to produce substantially neutral reaction "mixtures having apH value within the range 5.5 to 7.5, .as illustrated in Examples 1 and 20f that patent. The. isoamyl octylacid phosphateemployed is adi-ester of orthophosphoric acid having the following formula:

This compound is also known as 3-'methylbuty1,2-ethylhexyl acid orthophosphate. It readily reacts with cocoamine and otherprimary fatty amines containing from 8 to 18 carbon atoms. Instead of cocoamine we can use other primary fatty amines containing from 8 to 18 carbon atoms. These amines include mono-capryl,

CH3 (CH2) sCHzNI-Iz mono-lauryl, mono-myristyl, mono-palmityl and monostea'r'yl amines. The fatty acid amine salt of isoamyl octyl acid phosphate is preferably used in an amount between about 0.005 and about 0.2 percent by weight based onthe weight of the total composition.

The acid esters employed in accordance with this invention are the reaction products resulting from the esterification of a dimerized unsaturated fatty acid with a partial 'fatty acid'ester of an alkitol anhydride. The ratio of reactants rnay range from one mol of dimerized acid per 'mol ofpartial fatty acid ester up to the number of mols of dimerized acid that is equal to the number of free hydroxyl groups in the partial fatty acid ester, per mol of partial fatty acid ester.

The esterification reaction is effected in conventional manner and under conventional conditions. Thus, While esterifi'cation may proceed slowly at room temperature, thereaction is .normally advantageously accelerated by heating the reactants, usually with refluxing, and/or by the use of conventional esterification catalysts, such as hydrogen chloride, sulfuric acid, or an aromatic sulfonic acid, such as p-toluene-sulfonic acid. The reaction may bedriven to substantial completion by removing one of the/products of reaction. Since the herein disclosed dimeric unsaturated fatty. acids, partial esters of alkitol anhydrides, and their reaction products boil at a temperature substantially above the boiling point of water, the reaction conveniently may be driven to completion by removal ofthe water of esterificatioh by distillation. The removal of Water'from the reaction mixture may be facilitatedby mechanical agitation, or by bubbling an inert gas, such as nitrogen, through the reaction mixture.

By way of illustrating the foregoing process,-one, two or three mols of dimerized acid may be esterified with one mol of a partial fatty acid ester containing three free hydroxyl groups, under conventional reaction conditions, with the elimination, respectively, of one, two or three mols of water of esterification, to form, respectively, a mono-,dior tri-acid or tricarboxylic ester of the dimerized acid and the partial fatty acid ester.

Ifdesired, the reaction products may be prepared by eifecting-esterification of the reactants in mineral oil solution j This expedient isv advantageous in that it prevents localized overheating of the reactants. Moreover, the resuming reaction products-are in the form of mineral oil concentrates, the use of which "often facilitates solution of theadditives in their'ultirnate vehicles.

Th dim'eri'zed acids referred to above are dimers, i. e., bimolecularadditioriproducts 'of conjugated or unconj'u'gat'ed dienoic' or trienoic fattyacids having from 6 to 22 carbon atoms before dimerization. Dimeric acids derived from dienoic' and .trienoicfattyacids are well known and can be prepared by conventional methods which form no part of this invention.

More particularly, dimerized acids capable of forming the compounds utilized in'the 'composition of this invenso ata prepared from dienoic or trienoic-fatty acids having the' generic formula CnI'IZn-ZCOOH, where n is an integer of from to 2 1.and x is 3 or 5. As' will be evident, such monomeric acid'scontain from 6 to 2 2.Carbon-ato'ms and" may containZ or 3 ethyle'nic linkages as the ratio of carbon-to hydrogen'increases, i: e., as-x' increases from 3 to 5. Dimerized acids corresponding to "the addition products of the foregoing acids therefore may be defined by the generic formula:

0 ll C--OH QnHZn-z where n is an integer of from 10 to 42 and where x is an even integer of from 6 to 1 0. These dimeric acids are therefore dibasic or dicarboxylic acids having from 12 to 44 carbon atoms.

Representative members of the class of dimerized acids capable of forming the compounds employed in the compositions of this invention are dimers of dienoic acids such as sorbic (hexadienoic), linoleic (octadecadienoic), humoceric (nonadecadienoic) and eicosinic ('eicosadienoic) acids. Dimers of trienoic acids, for example, linolenic and eleostearic (octadecatrienoic) acids also may be used.

It is not necessary that both of the unsaturated fatty acid molecules of the bimolecular addition product be identical. Dimers of mixed composition such as those obtained by dimerizing mixed dienoic, mixed trienoic or mixed dienoic and trienoic acids such as may be derived from certain naturally occurring drying oils, e. g., linseed oil and soybean oil, are quite satisfactory.

Dienoic and trienoic acids having 18 carbon atoms, especially those having conjugated olefinic linkages, are preferred for reasons of economy of procurement, ease of reaction and the general excellence of the additives prepared therefrom.

The partial esters of alkitol anhydrides and fatty acids adapted for use in the formation of the reaction products are those resulting from esterification with the desired fatty acid of at least one, but less than all, of the available 'hydroxyl: groups of an alkitol anhydride. By alkitol anhydride is meant an intramolecular, monoor dianhydride of a polyhydric alcohol which contains at least 4 carbon atoms and at least 4 hydroxyl groups, or mixtures of said anhydrides. Representative of the class of alkitols are erythritol; pentitols,.such as arabitol, xylitol and adonitol; and hexitols such as mannitol, dulcitol and sorbitol, just as the xylitans and sorbitans are representative of the alkitol anhydrides, or alkitans.

Fatty acids. capable of forming partial esters of alkitol anhydrides suited to the preparation of the additives utilized in this invention are the fatty acids containing from 12 to 24 carbon atoms. These acids may be saturated or unsaturated, and they may be substituted with groups which do not adversely affect the oil-solubility'or corrosion-inhibiting properties of the final reaction product. Representative of this group of acidsare lauric acid, oleic acid, ricinoleic acid, stearicacid and lignostearic acid.

Partial esters capable of reacting to form the reaction products include those formed by reacting a fatty acid'of the foregoing kind with the desired alkitol anhydride in a molar ratio of at least 1:1, but less than that which would result in neutralization of all of the hydroxyl groups of the alkitol anhydride. The use of mixtures of partial fatty acid esters of alkitolanhydrides is also included within the scope of the invention. Specific examples of partial esters ofalkitol anhydrides capable of reacting with dimeric unsaturated fatty acids to form acid esters which can be used in the composition of the invention are xylitan and sorbitan mono-, sesqui-, diand trioleates and stearates. Partial esters of hexitol anhydrides, i. e., anhydrides of lpolyhydric alcohols containing 6 carbon atoms and 6 hydroxyl groups, are preferred.

The partial esters of alkitol anhydrides disclosed herein as well as the method of preparing the same are conven tional and form no part of the present invention. Art-7 cordingly,-theyneed notbe described. in detail. p

Representative specific examples of acid esters of dimeric acids with partial fatty acid esters of alkitans which can be used in the compositions of this invention are the monoand polycarboxylic acid esters of dimer ized linoleic, linolenic and eleostearic: acidswith sorbitan and xylitan mono-, sesqui-, diand trioleates and stearates. Included within the foregoing represehtativeclass of compounds are mono-, di-, and triacid dilinoleic mono-, diand triesters of sorbitan'monooleate, monoand diacid dilinoleic monoand diesters of sorbitan dioleate, mono-acid dilinoleic mono-esters ofsorbitan trioleate, monoand diacid dilinoleic monoand di esters of xylitan monooleate, mono-acid dilinoleic monoesters of xylitan dioleate, and corresponding acid esters made from dimerized linolenic and eleostearic acids, as well as those made from partial esters of stearic acid.

The preparation of the class of compounds useful in the compositions of the invention can be further illustrated by the following specific example;

Example I An acid ester of a dimeric unsaturated fatty acid and a partial fatty acid ester of an alkitol anhydride Was prepared by admixture and reaction of 428' parts by weight of sorbitan monooleate (manufactured by the Atlas Powder Company of Wilmington, Delaware, andmarketed under the nameSpan 80) with 560 parts by Weight of dimerized linoleic acid (manufactured by Emery Industries, Inc. of Cincinnati, Ohio, and marketed under the name of Emery 955 Dimer Acid). The'reaction "mixture was heated'under reflux, until 18 parts by weight of water had been trapped off, the maximum temperature reached by the reaction mixture being 500" F. The dimerized linoleic acid of this example had the following characteristics:

Physical state Straw-colored, viscous liquid.

Molecular weight 564 (approx.).

Gravity, "API 13.0.

Viscosity, SUV, 200 597.

Flash, 00, "F. 510.

Fire, 00, "F. 575.

Color, NPA a +10.

Iodine No., Mod. Hanus 83.3.

Saponification No. 186.

Neutralization No. 182.

Dimer content 85% (approx).

Trimer and higher 12% (approx).

Monomer 3% (approx.).

The properties of the sorbitan monooleate' were "as :follows: 1

Molecular weight 428 (approx) Gravity, "API 10.1. Sp. gr., 60/60 F 0.99 9. vLb./gal., 60 F 8.32. Viscosity, SUV:

210" F 108.3. Flash, P-M, "F 400. Flash, C, "F 410. Fire, 0C, "F 450. Pour, "F +10. Physical state, room temp Viscous liquid. Color, ASTM union 4.5. Water by distn, percent Nil. Carbon residue, Conradson, perc ent 2.94. Neutralization value, ASTM D974-51T,

total acid No; 615. 7

pH value, glass-calomel electrodes 7.0. Saponification No., ASTM D94-48T--. 14 9.0.

Acetyl value, Gulf 433 142.

Ash, per

The product obtained in the above-described reaction was a clear, viscous liquid containing predominantly mono-acid esters of dimerized linoleic acid and sorbitan monooleate, having the following physical properties:

Gravity, API 13.4. Sp. gr., 60"/60 F 0.977. Lb./gal., 60 F 8.13. Viscosity, SUV, sec: F 9936.

210 F 498. Flash, P-M, F 425. Pour, "F 0. Physical state, room temp Viscous liquid. Color, ASTM union"; 6.0. Neutralization value, ASTM D974-51T,

total acid No 70. pH value, glass-calomel electrodes 4.6.

The acid esters of other dimerized unsaturated fatty acids and other partial fatty acid esters of alkitol anhydrides are similarly prepared.

The amount of the acid ester employed in the compositions of the invention depends upon the amount of the fatty amine salt of isoamyl octyl acid phosphate which has been used. Satisfactory results have been obtained with weight ratios of acid phosphate to acid ester of 1:1 to 1:4. Based on the weight of the total composition when using these ratios, the amount of acid ester comprises about 0.005 to about 0.8 percent by weight of the total composition. In any event the acid ester is used in an amount sufiicient to prevent the formation of a precipitate when the composition is contaminated with a small amount of water.

The lubricating oil compositions of this invention can contain other additive agents if desired to improve other specific properties without deleteriously aifecting the beneficial properties of the compositions. For example, pour point depressors, viscosity and viscosity index improvers, dyes, sludge inhibitors and the like can be used. Also, if desired, the oil can contain a foam inhibitor such as organo-silicon oxide condensation products, organosilicol condensation products and the like.

The individual constituents of the compositions of this invention may be added to the lubricating oil base in any order or simultaneously, either per se or in the form of a mineral oil concentrate. The latter practice is sometimes desirable in order to facilitate compounding of the compositions.

To illustrate the improved properties of the compositions of the invention, separate samples of compositions contaminated with water were compared with the base oil and other compositions containing an acid ester. The

base oil used in the test was a highly refined aluminum chloride treated paraffinic turbine oil stock having an API gravity between about 30.5" and 32.5" and a viscosity of about SUS at 100" F. In each instance the oil also contained 0.0033 percent by weight of Dow- Corning silicone Fluid 200 as a foam inhibitor. In order to determine the stability of the compositions the separate samples were stored in the sunlight in glass containers for 20 days. At the end of the 20-day period, the samples were examined for precipitate and for haze. V

The improved rust-inhibiting properties of the compositions of the invention have been demonstrated by subjecting the separate samples to the procedure of ASTM test D943-47T. Briefly, this test is carried out by passing oxygen at a measured rate of 3 liters per hour into an oil-water mixture maintained at 203" F. and having an iron coil immersed therein. According to the procedure followed herein, the test was carried out for 500 hours. The corrosion-inhibiting properties of the compositions were determined by examining the iron coil before and after completion of the test. The amount of rust on the composition in preventing rust.

nastiest The results of the 20-day storage test and the ASTM D94347T te'st are tabulated as follows:

having-"from 2 to 3 ethylenic'linkages ei-molecule and (2) apartial estergof ajatty acidcontaini-ng 18 carbon Composition, percent by wt A B Base oil 2, fi-di-tertiaryrbu 1-4-methy1phen0l. Zinc dihexyl thio'p osphate Coeoamine isoamyl oot lorthophosphate Dimerized linoleic aci -sorbitan monooleate acid ester reaction'produet of Example I.

nil medium." nil. nil medium... nil. light light bright.

rust rust.

As can berioted from the data in the above table, the base oil gav'e satisfactory performance in the stability tests. Likewise the base oil containing 0.5 percent by weight of' water was satisfactory. Even composition C passed the sunlight stability test when there was no water present. However, when 05 percent by weight of I water was added to composition C the composition formed a medium amount of precipitate and haze after days of exposure (composition D). It will be further noted, however, that when a. small amount of the acid ester was employed, there was substantially no precipitate and no haze (composition E). Thus, as evidenced byv composition E, the compositions of the invention resist the formation of precipitate and haze even when contaminated with water. As further evidenced from-the data in the above table, the compositions of the invention in addition to having improved storage stability also give greater protection against rusting.

While the invention has been described above with reference to certain specific embodiments thereof by way of illustration, it is to be understood that the invention is not limited'to such embodiments except as hereinafter defined in the appended claims.

We claim: a

1. 'An improved turbine oil consisting essentially of a major proportion of a mineral lubricating oil and minor proportionsconsisting of'about 0.1 to about 2.0 percent by weight of an alkyl phenol, said alkyl phenol containing alt-least one alkyl group containing between 3 and 12 carbon atoms, about 0.01 to about 0.1 percent by weight of a metal alkyl thiophosphate, said alkyl group containing between 3 and 12 carbon atoms, about 0.005 to about 0.2 percent by weight of a substantially neutral addition product of 3-methylbutyl,Z-ethylhexyl acid orthophosphate and a primary fatty amine, said amine being a mono-alkyl amine containing from 8 to 18 carbon atoms, and about 0.005 to about 0.8 percent by weight of an acid ester of (1) a. dimeric' acid derived from an unsaturated fatty acid containing from 6 to 22 carbon atoms and having from 2 to 3 ethylenic linkages per molecule and (2) a partial ester of a fatty acid containing from 12 to 24 carbon atoms and an alkitol anhydride, said acid ester containing at least one unreacted carboxyl group per molecule.

' 2. An improved turbine oil consisting essentially of a major proportion of a mineral lubricating oil and minor proportions consisting of about 0.1 to about 2.0 percent by weight of an alkyl phenol, said alkyl phenol containing at least one alkyl group containing between 3 and 12 carbon atoms,-about 0.01 to about 0.1 percent by weight of a metal alkyl thiophosphate, said metal being a metal of group II of the-periodic system and said alkyl thiophosphate containing at least one alkyl group containing between 3 and 12 carbon'atoms, about 0.0055to-ab0ut 0.2 percent by weight of the cocoamine salt of 3-methylbutyLZ-ethylhexyl acid orthophosphate, and about 0,005 toabout 0.8 percent by weightofan acid ester ot (1) a dimeric acid derived fromran: un-; saturated fattty acid containing 18 carbon atoms and,

-= p o ontaini g. t e t lone. k roup mn ai in atoms and a hexitol anhydride, said acid ester containing at least one unreacted carboxyl group per molecule.

3. An improved turbine oil consisting essentially of a major proportion of a mineral lubricating oil and minor proportions consisting of about 0.1 to about 2.0 percent by weight of a tertiary alkyl phenol, said tertiary alkyl phenol containing at least one alkyl group con taining between 3 and carbon atoms, about 0.01 to about 0.1 percent by weight of a metal alkyl thiophosphate, said metal being a-metal of group II of the per= iodic system and said alkyl thiophosphate containing at least one alkyl group containing between 3 and 12 carbon atoms, about 0.005 to about 0.2 percent by weight of the cocoarnin'e salt of 3-methylbutyl,2-ethylhexyl acid orthophosphate, and about 0.005 to about 0.8 percent by weight of an acid ester of a dimer of linoleic acid and sorbitan monooleate, said acid ester containing at least one unreacted carboxyl group per molecule.

4. An improved turbine oil consisting essentially of a major proportion of a mineral lubricating oil and minor proportions consisting of about 0.1 to about 2.0 percent by weight of a tertiary alkyl phenol, said tertiary alkyl phenol containing at' least one alkyl group containing between 3 and 12 carbon atoms, about 0.01 to about 0.1 percent by weight of a metal alkyl thiophosphate, said metal being a metal of group II of the periodic system and said alkyl thiophosphate containing at least one alkyl-group containing between 3 and 12 carbon atoms, about 0.005 to about 0.2 percent by weight of the cocoamin'e' salt of 3-methylbutyl,2-ethylhexyl acid orthophosphate,..and an acid ester of a dimer of linoleic acid and sorbitan monooleate, said acid ester containing at least one unreacted carboxyl group per molecule and wherein said acid ester is present in an amount sufiicient to prevent the formation of a precipitate when said turbine oil is contaminated with water.

5.'An improved turbine oil consisting essentially of a major proportion of a mineral lubricating oil and minor proportions consisting of about 0.1 to about 2.0 percent by weight of a tertiary alkyl phenol, said tertiary alkyl phenol containing at least one alkyl group containing between 3 and 12 carbon atoms, about 0.01 to about 0.1 percent by weight of a metal alkyl thiophosphate, saidmetal being a metal of group II of the periodic systemand said alkyl thiophosphate containing at least one alkyl group containing between 3 and 12 carbon atoms, about'0.005 to about 0.2 percent by weight of the cocoarnine salt of 3-methylbutyl,2-ethylhexyl acid orthophosphate, and an acid ester of a dimer of linoleic acid and sorbitan monooleate, said acid ester containing at least oneunreacted carbonyl group per molecule and wherein the w eightratio of the cocoamine salt of 3- methylbutyl',2;;gethylhexyl acid orthophosphate to said acid ester is between about 1:1 and 1:4.

6. An improved turbine oil consisting essentially of a major proportion of a mineral lubricating oil and minor proportionsconsisting ofabout 0.1 toabout 2.0 percent y weight ot sei ert ar .alky rbeuob said er a y alky between 3 and 12 carbon atoms, about 0.01 to about 0.1 percent by weight of a metal di-alkyl thiophosphate, said metal being a metal of group II of the periodic system and said di-alkyl thiophosphate containing at least one alkyl group containing between 3 and 12 carbon atoms, about 0.005 to about 0.2 percent by weight of the cocoamine salt of 3-methylbutyl,2-ethylhexyl acid orthophosphate, and an acid ester of a dimer of linoleic acid and sorbitan monooleate, said acid ester containing at least one unreacted carboxyl group per molecule and wherein the weight ratio of the cocoaminesalt of 3- methylbutyLZ-ethylhexyl acid orthophosphate to said acid ester is between about 1:1 and 1:4.

7. An improved turbine oil consisting essentially of a major proportion of a mineral lubricating oil and minor proportions consisting of about 0.1 to about 2.0 percent by weight of a tertiary butyl cresol, about 0.01 to about 0.1 percent by weight of a metal di-alkyl thiophosphate,

tern and said di-alkyl thiophosphate containing at least 20 one alkyl group containing between 3 and 12 carbon atoms, about 0.005 to about 0.2 percent by weight of the cocoamine salt of 3-methylbutyl,2-ethylhexyl acid orthophosphate, and an acid ester of a dimer of linoleic acid and sorbitan monooleate, said acid ester containing 10. at least one unreacted carboxyl group per molecule and wherein the weight ratio of the cocoamine salt of 3- methylbutyl,2-ethylhexyl acid orthophosphate to said acid ester is between about 1:1 and 1:4.

8. An improved turbine oil consisting essentially of a major proportion of a mineral lubricating oil and minor proportions consisting of about 0.1 to about 2.0 percent by weight of 2,6-di-tertiary-butyl-4-methylphenol, about 0.01 to about 0.1 percent by weight of zinc dihexyl thiophosphate, about 0.005 to about 0.2 percent by weight of the cocoarninc salt of 3-methylbutyl,Z-ethylhexyl acid orthophosphate, and about 0.005 to about 0.8 percent by weight of an acid ester of a dimer of linoleic acid and sorbitan monooleate, said acid ester containing at least one unreacted carboxyl group per molecule.

References Cited in the file of this patent UNITED STATES PATENTS 2,364,283 Freuler Dec. 5, 1944 2,371,655 Smith et a]. Mar. 20, 1945 2,631,979 McDermott Mar. 17, 1953 FOREIGN PATENTS 428,864 Great Britain May 15, 1935 

1. AN IMPROVED TURBINE OIL CONSISTING ESSENTIALLY OF A MAJOR PROPORTION OF A MINERAL LUBRICATING OIL AND MINOR PROPORTIONS CONSISTING OF ABOUT 0.1 TO ABOUT 2.0 PERCENT BY WEIGHT OF AN ALKYL PHENOL, SAID ALKYL PHENOL CONTAINING AT LEAST ONE ALKYL GGROUP CONTAINING BETWEEN 3 AND 12 CARBON ATOMS, ABOUT 0.01 TO ABOUT 0.1 PERCENT BY WEIGHT OF A METAL ALKYL THIOPHOSPHATE, SAID ALKYL GROUP CONTAINING BETWEEN 3 AND 12 CARBON ATOMS, ABOUT 0.005 TO ABOUT 0.2 PERCENT BY WEIGHT OF A SUBSTANTIALLY NEUTRAL ADDITION PRODUCT OF 3-METHYLBUTYL1,2-ETHYLHEXYL ACID ORTHOPHOSPHATE AND A PRIMARY FATTY AMINE, SAID AMINE BEING A MONO-ALKYL AMINE CONTAINING FROM 8 TO 18 CARBON ATOMS, AND ABOUT 0.005 TO ABOUT 0.8 PERCENT BY WEIGHT OF AN ACID ESTER OF (1) A DIMERIC ACID DERIVED FROM AN UNSATURATED FATTY ACID CONTAINING FROM 6 TO 22 CARBON ATOMS AND HAVING FROM 2 TO 3 ETHYLENIC LINKAGES PER MOLECULE AND (2) A PARTIAL ESTER OF A FATTY ACID CONTAINING FROM 12 TO 24 CARBON ATOMS AND AN ALKITOL ANHYDRIDE, SAID ACID ESTER CONTAINING AT LEAST ONE UNREACTED CARBOXYL GROUP PER MOLECULE. 